1. Field of the Invention
The invention relates to decontamination of chemical warfare agents. More particularly, the invention relates to the decontamination of mutated agents such as HD by oxidation, as well as nerve agents such as VX and GD by perhydrolysis, using environmentally safe activated hydrogen peroxide. The peroxide is activated at lower pH, thus rendering it more stable than such prior decontaminating solutions.
2. Background
Several types of toxic chemical compounds are known to be useful as chemical warfare agents. These include mustard agents or gases known as blister agents, such as bis-(2-chloroethyl) sulfide, also known as HD, and nerve agents such as pinacolyl methylphosphonofluoridate, which is also known as GD, and O-ethyl S-(2-diisopropylamino)ethyl methylphosphonothioate, which is known as VX. HD is a colorless, oily liquid that is highly insoluble in water, and is a powerful vesicant which primarily affects the eyes and the lungs, blisters the skin and is considered a carcinogen. HD is also cytotoxic to hematopoietic tissue and can be lethal at high doses. GD and VX are powerful nerve agents that attack the nerve cells and impair the functioning of the central nervous system.
In order to decontaminate the vesicant mustard gas to render it non-toxic, it is necessary to oxidize it to the corresponding sulfoxide. Nerve agents such as VX and GD are rendered non-toxic by perhydrolysis to their non-toxic phosphonic acids. For example, the oxidation of HD to HD-sulfoxide (HDO) renders the gas non-toxic. One effective way to conduct this oxidation reaction is by reacting the agent with peroxide compounds.
Mildly-basic peroxide is also known to effect the perhydrolysis of VX and GD to their non-toxic phosphonic acids. Peroxides are desirable reactants for decontamination because they are non-toxic and non-corrosive, as compared to hypochlorite-based processes which are toxic and environmentally harmful. Additionally, peroxides are preferable because of their extremely low freezing points. However, while it is desirable to decontaminate chemical warfare agents by oxidation in a peroxide system, presently known systems are inefficient decontaminates because they cause secondary oxidation of the corresponding sulfoxide to a sulfone, a toxic vesicant. For example, HD-sulfoxide is a non-vesicant, while HD-sulfone is a highly toxic vesicant material. Also, known peroxide systems using hydrogen carbonate ions as an activator are inefficient because the oxidation reaction is very slow. However, hydrogen carbonate activator is efficient at generating peroxy anion (OOH−) for VX and GD perhydrolysis. The oxidation reaction of HD may be greatly enhanced using molybdate activator, which selectively oxidizes HD to its sulfoxide, while avoiding the formation of HD sulfone. Additionally, molybdate does not interfere with the rapid, simultaneous perhydrolysis of VX and GD. Thus, bicarbonate and molybdate activators, in combination with hydrogen peroxide, provide for the fast and efficient decontamination of both nerve agents VX and GD and blister agent HD. However, such solutions of hydrogen peroxide activated with bicarbonate and molybdate are not stable for extended periods of time as hydrogen peroxide is not stable at basic pH.
U.S. Pat. No. 6,245,957 to Wagner et al., incorporated by reference, discloses a chemical warfare agent decontaminating composition of a mixture of a carbonate component, a peroxide component and an alcohol component effective to degrade a chemical warfare agent.
U.S. Pat. No. 6,723,891 to Wagner et al., incorporated by reference, discloses a process for the decontamination of chemical warfare agents, such as a process for the decontamination of the vesicant HD by oxidation to its corresponding sulfoxide and nerve agents VX and GD by perhydrolysis to their non-toxic phosphonic acids using environmentally safe reactants, specifically a peroxomolybdate compound having a dominant tetraperoxomolybdate species and peroxy anion.